Comet Skyray
02-27-2010 | 03:25 PM
#1
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Comet Skyray
Comet Skyray
I want to build an Elec. Duct. Fan model of the Douglass Skyray using the Comet (of Chicago) plan as an example. It is of 15 1/2 inch wingspan, for kit Y-9, and already has a flat bottom airfoil.
Considering the weight of R/C receiver, servos, batteries and a Kress EDF (like an RK-709E unit), how much should I increase the wing area in order to convert this Comet Skyray glider in to a powered unit? I have not made an estimate as to wing area or loading as per original plan yet.
How big of a tailcone and inlet ought to be required too?
Or, has this been done before, and a plan made up then?
Wm.
I want to build an Elec. Duct. Fan model of the Douglass Skyray using the Comet (of Chicago) plan as an example. It is of 15 1/2 inch wingspan, for kit Y-9, and already has a flat bottom airfoil.
Considering the weight of R/C receiver, servos, batteries and a Kress EDF (like an RK-709E unit), how much should I increase the wing area in order to convert this Comet Skyray glider in to a powered unit? I have not made an estimate as to wing area or loading as per original plan yet.
How big of a tailcone and inlet ought to be required too?
Or, has this been done before, and a plan made up then?
Wm.
02-27-2010 | 03:32 PM
#2
RE: Comet Skyray
Coos, perhaps start by letting us know what the overall weight is of this items you've got. Also a good way to look at what size to make this one is to look at other designs using the same power unit as to wing area and weight.
Being a single wing you'll want to size it a bit bigger for area than the equivalent standard configuration of wing and stabilizer. I like to think of it as needing to have more area because part of the wing surface at the rear is acting like the horzontal stabilizer. But the real reason is due to the flying wing needing to use a reflexed positive pitch stability airfoil that is not able to reach as high a lift coefficient as a "regular" airfoil so to compensate a little more wing area is used to be able to slow down to the same speed.
Same for the duct inlet and outlet areas. For stuff like this it's nice to plagarize from other successful designs if you can't get any meaningful data from the maker.
Being a single wing you'll want to size it a bit bigger for area than the equivalent standard configuration of wing and stabilizer. I like to think of it as needing to have more area because part of the wing surface at the rear is acting like the horzontal stabilizer. But the real reason is due to the flying wing needing to use a reflexed positive pitch stability airfoil that is not able to reach as high a lift coefficient as a "regular" airfoil so to compensate a little more wing area is used to be able to slow down to the same speed.
Same for the duct inlet and outlet areas. For stuff like this it's nice to plagarize from other successful designs if you can't get any meaningful data from the maker.
02-27-2010 | 04:54 PM
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RE: Comet Skyray
ORIGINAL: BMatthews
Coos, perhaps start by letting us know what the overall weight is of this items you've got. Also a good way to look at what size to make this one is to look at other designs using the same power unit as to wing area and weight.
Same for the duct inlet and outlet areas. For stuff like this it's nice to plagarize from other successful designs if you can't get any meaningful data from the maker.
Coos, perhaps start by letting us know what the overall weight is of this items you've got. Also a good way to look at what size to make this one is to look at other designs using the same power unit as to wing area and weight.
Same for the duct inlet and outlet areas. For stuff like this it's nice to plagarize from other successful designs if you can't get any meaningful data from the maker.
At this time, I do not have an estimate as to overall weight as mentioned.
I do know the folks at Kress had one problematic time in getting the proper inlet and outlet sizes. One affects the other.
Wm.
02-28-2010 | 09:33 AM
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RE: Comet Skyray
ORIGINAL: BMatthews
Yes they do. And you can set up the combo for either low or high speed as I understand from reading about the issues.
Yes they do. And you can set up the combo for either low or high speed as I understand from reading about the issues.
Well, I got copies of the older P.E. Norman D.F. experiments, but most A/C are British Hawker types, and his plans always seem to NOT show up the C.G. They are over the top on glow engine power, and how to built this thing (like a fan) in trippliate in alternatives.
Wm.
